Diacylated pteroic acid and process for preparing same



Patented July 18, 1950 UNITED D1ACYLATED r'riiaolo ACID AND PROCESS .FOR, PREPARING SAME 11mm. wolanahwamana Karl Folkers, Plainfield,,N. J., assignors to Merck & 00., Inc., Rah: way, N. J a corporation of New Jersey No Drawing.

droxy-fi-pteridyl)methyll acylamino) benzoic acid can be represented by the formula:

wherein R represents an acyl substituent and R" represents an acyl substituent'bfthe v class consisting of the formylgroup and the acyl, group R.

In accordance compounds may be prepared by acyl'ating compounds ofthe general-formula:

wherein represents hydrogen andfo sub:

stituents. A compoundof, this general structure wherein R, is a formyl roup isafulilyfdefined by the chemical name 4-([(2eaminoe4 hydroxy fi9 with our invention these: new

pteridyl) methyll formylamino) benzoic acid, 1 and will hereinafter be referred to as rhi This compound, rhizopterin. is the pt acidic chemical compound obtained fro' 'fumaric acid fermentation liquor. This general process and rhizopterin thereby securedis disclosed and claimed in a copending application; to our colleagues, Keresztesy and RickesfSeriaI 'No.

536,434, filed May 19, .1944, now Patent No. 2,478,404.

A compound of the above formula wherein R is hydrogen is fully defined by the chemical, name 4-([(2-amino-4-hydroxy 6 pteridyDmethyl]:

amino)benzoic acid and will hereinafter be referred to as aporhizopterin. Thiscompound,

aporhizopterin, is obtained by, alkalinefdeacyla 5 tion of rhizopterin in accordance with a proce- Application August 10, 1946, Serial No. 689,814

12 Claims. (01. 260251) dure described in the copending application by our colleagues, Keresztesy and Rickes, Serial No. 731,868, filed March 1, 1947. Since rhizopterin contains one formyl group in the molecule, it is capable of adding one additional acyl substituent. While aporhizopterin contains no acyl groups, it is capable of adding two acyl substituents to the molecule. It will be apparent that formylation of rhizopterin or aporhizopterin results in the same compound, 4- E (2 f0rmy1amino-4-hydr0xy- S-pteridyl) methyllformylamino) -benzoic acid, which is referred to as formyl rhizopterin.

The process in accordance with our invention comprises reacting rhizopterin or aporhizopterin with an acylating agent and recovering the acyl derivative of these compounds. Rhizopterin or aporhizopterin can either be reacted with the required quantity of the acyl compound in the presence of an organic solvent or an exces of the acylating compound can be employed for a solvent effect. The reaction mixture is heated until allof the solid material present has been dissolved. After completion of the reaction, the organic solvent and excess acylating agent may be removed by evaporation. I Alternatively, any excess acylating agent present in the reaction mixture can be decomposed with alcohol and theQac'ylated derivative precipitated from ether. A pure compound, can be obtained by dissolving the crude acyl derivative of rhizopterin or aporhizopterin in ammonium hydroxide and acidifying the solution with acetic acid to precipitate the acylated derivative. It has been found that formyl rhizopterin can not be crystallized in this manner since treatment of this compound with alkali and acid hydrolyzes the formyl group in the 2-po'siti0n and rhizopterin is obtained. 7

The following examples set forth a method of carrying outlthe present invention, but it is to be understood that these examples are given by way of illustration and not of limitation.

Example 1 Approximately!) mg. of rhizopterin were refiuxed with} ml. of formic acid (98%) until all ofthe solid had dissolved. The solution was then concentrated to dryness in vacuo. The formyl rhizopterin, i. e. 4-([(2-formylamino-4-hydroxy- G-pterid'yl) methyllformylamino) benzoic acid was deposited as a nearly white solid residue which was dried at C.'for analysis.

Anal.-Calcd. for C16H1zNeO5; lxT, 22.82. Found;

Example .2

Approximately 23 mg. of rhizopterin were suspended in a mixture of 1 cc. pyridine and 1 cc. acetic anhydride. The mixture was heated on a steam bath for 30 minutes to achieve complete 5 solution, and was then concentrated to dryness in vacuo. The solid residue obtained consisted of acetyl rhizopterin, i. e. 4-([(2-acetylamino-4- hydroxy 6 pteridyl)methyllformylamino)benzoic acid. A pure compound was obtainedby dis-. 10 solving the crude product in dilute ammonium hydroxide and acidifying the solution with acetic acid at a temperature of 90 to 100 C. to effect precipitation of the nearly white crystalline solid.

Acetyl rhizopterin showed activity in promoting growth of S. lactis R. Anal.Calcd. for C1'1H14NsO5: C, 53.40; H, 3.69; N, 21.98. Found: C, 53.83; H, 4.01; N, 22.65.

Example 3 Approximately 10 mg.. of rhizopterin .were.'dissolved in acetic anhydride by heating at 100 C. The excess aceticanhydride was. evaporated in vacuo leaving a. nearly: white residue. of acetyl .25 rhizopterin. Purification was accomplished by dissolvin the crude product in dilute ammonium hydroxide and acidifying with acetic acid at 90. C. until the acetyl rhizopterin precipitated.

The pure compound has the following characteristic ultraviolet absorptionspectrum:

Wave le ngths 13% 2,575 985 PE g. 232 .ggg 3:400 @191 Example 4 Example 5 00 15 mg. of rhizopterin-were treated." with 'approximately 3 cc. of benzoic anhydridei at 180-' 200 C. until allsolidrmatteri-was dissolved. The excess benzoic anhydride was decomposed with alcohol and the solution-was-diluted with pe- 65.

troleumethen- -Benzoyl rhizopterin si. e. 4- (2,-

benzoylamino' 4 hydroxy fi pteridyh methyll formylamino) benzoic acidprecipitated from the. mixture. A pure compound .was'obtained by dissolving the crude product. in dilute ammonium 70..

hydroxide and slowlyacidifying the solution with, v acetic acid. The pure benzoyl rhizopterin ob-. tained in this manner. had a melting. point of 255.-.-258-- C- It was biologically active. in the growth of S. lactis R.

Example 6 3 mg. of rhizopterin were suspended in 2 cc. pyridine and treated with 0.2 g. of phenylacetic anhydrlde. The mixture was heated at 100 C. until all solids were dissolved. The solution was concentrated :in vacuo leaving a brown oil as a residue. Addition-of ethericaused precipitation of phenylacetyl rhizopterin, i. e. 4-([(2-phenylacetylamino 4 hydroxy 6 pteridyl) methyl]- formylamino) benzoic, acid. Purification was accomplished by dissolving the crude product in dilute ammonium hydroxide and slowly acidifying the solution with acetic acid until the phenylacetyl-rhizopterin precipitated. The pure product had a melting point of 276 C.

Anal.-.Calcd for C23H18N6052 C, 60.26; H, 3.96; N, 18.34. Found: C, 60.51; H, 4.42; N. 18.55.

Example 7 Approximately 8 mg. ,of rhizopterin were dissolved-in an excess-,-.of,; phenylacetic. anhydride by heatingon the steambath. ,The excess phenylacetic anhydride was decomposed by additionof methanolvand the resulting solution was. conce n trated in vacuo to asmall-yolume. --Addit'iOn;Ol; ether causedtprecipitatiop of the; phenylacetyl. rhizopterin, -.i. e. 4-([ (2 phenylacetylamino-4 hydroxy- 6 ridrmnethr lfi rm em n benzoic acid. This crude product was purifiedby dissolving it in dilute ammoniumrhydroxide and slowly.acidifying:thesolutionwithaceticacid at -100- C. "fPLllflB -.phenylacety1 rhizopt,erin crystallized in white. needles .;hav in'g-.- a melting point of 276 (3.

Example 8 About 25 mgtofuaporhizopterin were suspended in a mixture of 2 ml. of formic acid (88%) and 0.7 ml. of acetic anhydride. The mixture was refluxed until an of t solid material .had dissolved. The solution. was then concentrated to dryness. The solid residue obtained consisted; of formyl rhizopterin. This residue was dissolved in diluteammolli lm hydroxide and acidified with acetic acid whereuponmhiz'opterin, precipitated as a pure crystalline prqdupt.

AnaL-Calcd. for C15H12Ne04r' C, 52.94; H, v 3.56. Found: C, 52.57; H, 3.24.

Example!) 9 mg. of aporhizopterin were suspended in 1 cc. of dry pyridine and the suspension was treated with 1 c-o apet caph r d a .10 fOr 6 hours. After .nearly. vall solid jmatter, had dis-j solvedthe utiq as. er porat d. n va 3W". ing acetyl, aporhizopterin, .1. e. A-(LZ-acetylamino 4 hydroxyefirpteridyllm thyllacetyl: .amino) benzo maic d as ane t yw ite solid. .T s crude product yvas. purified byflissolying it in dilute ammonium, hydroxide, and acidifying the olut on w th... et .c acid..." ure a ty .ap rhizopterin..ql stallized out in micrqneedles.

Example 10 10 mg. of aporhizopterin-were refluxed in acetic anhydride until; almost all material had dissolved. The solution was evaporated -;i n vacuo leaving acetyl aporhizopterin as a residue. -Thiscrude product was purified by dissolving in dilute am--- ,monium hydroxide and slowl-y, acidi fying the-so-;;

Wave le ngths E inA.

Modifications may be made in carrying out the present invention without departing from the spirit and scope thereof, and we are to be limited only by the appended claims.

We claim:

1. As a new composition of matter, a compound having the structural formula CHO wherein R. is selected from the group which consists of formyl, acetyl, methoxyacetyl, benzoyl and phenylacetyl radicals.

2. 4-( (2-formylamino-4-hydr0xy-6-pteridyl) methyl] formylamino) benzoic acid.

3. 4 (E(2-acetylamino-4-hydroxy-G-pteridyl) methylJformylamino) benzoic acid.

4. 4-([(2 benzoylamino-4-hydroxy 6 pteridyl) methyl] formylamino) benzoic acid.

5. 4-([(2 methoxyacetylamino 4 hydroxy- G-pteridyl) methyl] f ormylamino) benzoic acid.

6. 4 ([(2 phenylacetylamino 4 hydroxy- G-pteridyl) methyl] formylamino) benzoic acid.

7. The process that comprises reacting a compound of the formula CHO with an acylating agent selected from the group which consists of formic acid, acetic anhydride, methoxyacetic anhydride, benzoic anhydride and phenylacetic anhydride and recovering a com pound of the formula CHO wherein R is the corresponding acyl radical.

8. The process that comprises reacting 4([(2-= amino-4-hydroxy 6 pteridyl) methyllformyl amino) benzoic acid with formic acid and recover ing 4-( [(2 formylamino-4-hydroxy-G-pteridyl) methyl] formylamino) benzoic acid.

9. The process that comprises reacting 4-([(2 amino-4-hydroxy 6 pteridyl)methyl]formy1- amino) benzoic acid with acetic anhydride and recovering 4 ([(2 acetylamino 4 hydroxy- G-pteridyl) methyl] formylamino) benzoic acid.

10. The process that comprises reacting 4-([(2- amino-4-hydroxy 6 pteridyDmethyllformylamino benzoic acid with benzoic anhydride and recovering 4-([(2 benzoylamino 4 hydroxy- G-pteridyl) -methyl] formylamino) benzoic acid.

11. The process that comprises reacting 4-( [(2- amino-4-hydroxy 6 pteridyl)methyl]formy1- amino) benzoic acid with methoxyacetic anhydride and recovering 4 ([(2 methoxyacetylamino-4-hydroxy 6 pteridyl) methyllformylamino) benzoic acid.

12. The process that comprises reacting 4- (2- amino-4-hydroxy 6 pteridybmethyllformyh amino)benzoic acid with phenylacetic anhydride and recovering 4- (2-phenylacetylamino-4-hydroxy 6 pteridyl) methyllformylamino) benzoic acid.

' DONALD E. WOLF.

KARL FOLKERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,442,836 Angier June 8, 1948 FOREIGN PATENTS Number Country Date 206,454 Germany Feb. 23, 1908 OTHER REFERENCES Textbook of Organic Chemistry by George H. Richter, 1938 edition (Wiley) pp. 236 and 499.

Science, May 31, 1946, pp. 667-669. 

1. AS A NEW COMPOSITION OF MATTER, A COMPOUND HAVING THE STRUCTURAL FORMULA
 8. THE PROCESS THAT COMPRISES REACTING 4-(((2AMINO-4-HYDROXY - 6 - PTERIDYL)METHYL)FORMYLAMINO)BENZOIC ACID WITH FORMIC ACID AND RECOVERING 4-(((2-FORMYLAMINO -4- HYDROXY-6-PTERIDYL)METHYL)FORMYLAMINO)BENZOIC ACID. 